Why does power quality matter in medical applications? In any case, this is a very specific question. However, we will try to answer this question for you in this blog.

However, before providing possible answers about power quality in medical applications, we should shed light on the definition of power quality.

What is power quality in general?

Network quality is not a new topic. In recent years, however, it has come under increasing scrutiny due to the high degree of technologization and its vulnerabilities. This is expressed by so-called network phenomena. These in turn are derived from the standardization for electromagnetic compatibility(EMC) according to IEC 61000-x-x.

At first glance, we have a very reliable supply of electrical energy. At second glance, however, we encounter phenomena in the electrical network all the time. These, in turn, can lead to serious problems for people, machines and the environment, either individually or in aggregate. And this with a strongly growing tendency.

However, at the latest with the start of a so-called energy turnaround, the voltage quality in electrical distribution networks (= network quality) is becoming increasingly important. Ideally, the voltage in electrical networks has a sinusoidal shape. This is determined by voltage level, frequency and curve shape.

Thus, the power quality in medical applications is of high importance.

But what has changed now in terms of power quality in medical applications?

Due to the interaction of changed grid conditions and the increased use of non-linear consumers and generators, phenomena are increasingly occurring. As a result, the individual sinusoidal shape of current and voltage is influenced. This leads to changes in the power quality and can cause unwanted symptoms for other consumers. That, in turn, is a potential trigger of unplanned costs for medical device operators.

The challenges for medical facilities

The standard case for medical facilities, such as hospitals, university hospitals, rehabilitation clinics, specialized doctors, etc., looks like this (of course, not exhaustive):

• Operation of a relevant number of very expensive and technically complex plants
• High level of electronics and computers
• During the application, a high but short energy demand often acts on the network
• The staff is at the highest trained level
• The machines must yield a short ROI and thus function highly efficiently
• Patient safety is always the top priority

But what does power quality in medical applications have to do with it? Everything is on the highest technical and personnel level! After all, it all cost a lot of money.

An example

In addition to the actual medical challenges, technical malfunctions are a very unpopular chapter. Imagine that during a magnetic resonance imaging (MRI) scan, the equipment suddenly fails. The patient, in his already predicament, moves back out of the MRI and the system is restarted. Everything starts all over again. Bravo. And this several times that day. Called technicians can not solve the problem. The manufacturer’s service technicians are also baffled.

Conclusion of the operator: “Sh… equipment. I wish we had bought from another manufacturer!” Or is there something else going on here?

Issues of sudden failure or malfunction are becoming more frequent. And this in all areas of daily life.

But what may have happened now?

The solution to the riddle is not trivial and may well involve a corresponding degree of complexity. But you can already draw a conclusion here. When technical things happen that cannot be explained at first even by your technical staff, it may well have to do with the power quality in medical applications. Here again the phenomena of power quality according to the definition IEC61000-xx-xx play a role. These are:

• Irregularities in the mains frequency
• The level of a supply voltage
• Flicker
• Dips and/or surges in the supply voltage
• Rapid voltage changes (RVC)
• Voltage interruptions
• Asymmetry of the supply voltage (unequally loaded conductors)
• Harmonics in the system
• Interharmonic voltages (by the way also in signal transmission)
• Transients

What are the “influencers” of a change in network quality in medical applications

Modern power electronics and non-linear consumers are placing an increasing burden on electrical grids. As a result, the alternating current no longer shows the original sinusoidal curve as is the case with classic ohmic consumers (e.g. incandescent lamps, directly operated asynchronous motors, etc.)

Was sind die “Einflussfaktoren” für eine Veränderung der Netzqualität bei medizinischen Anwendungen? This is reflected in increased heat losses, rising energy consumption and even the malfunction and failure of systems.

In addition, there is the change from centralised power generation with an easily plannable unidirectional flow direction of the electricity in the distribution network. Today we have volatile electricity grids, supplemented by alternative energy producers, with a multidirectional flow direction. The electricity here is no longer produced exclusively by dynamo-electric generators, but increasingly by DC energy sources. These are usually led via DC / AC converters to an approximately sinusoidal consumer.

What symptomscan occur with altered power quality in medical applications?

The list of possible errors is long. Symptoms due to affected power quality in medical applications and environments may be as follows:

• Overheating of motors & transformers
• Unwanted disconnection of residual current devices and fuses, if present in the network (note IT networks).
• Neutral conductor overload = fire hazard (note IT networks).
• Overloading the Power Factor Correction capacitors
• Flickering of illuminants as well as monitors (in the meantime also no longer optically perceptible for humans)
• Failure of electronic ballasts
• General functional impairment of electronic equipment & controls (e.g. elevator controls, telephone systems, MRI, CT, X-ray systems, ultrasound applications, ECG, EEG, laboratory equipment, dialysis equipment, UPS systems, monitoring systems, surgical robots, computers, air conditioning equipment, air treatment equipment, oxygen controls, printers, etc.).
• Unintentional shutdown of servers (e.g. in the data center of a clinic)
• Interference with the transmission of ripple control signals
• Interference as well as false alarms from radio-networked smoke alarms
• Increased reactive energy and therefore increased energy costs (ǂ energy efficiency)
• Reduction of the expected lifetime of components (e.g. failure of LED lighting, failure of servers, motor failure, transformer failure, etc.)
• Disturbing noise development (in the frequency range up to 16 kHz for the human ear)
• Skin effects as the tendency of a high-frequency alternating current to flow only through the outer layer of a conductor
• Line and cable damages
• etc.

And now? What should I do?

In order for you to escape the problem of poor network quality, it is similar to a patient diagnosis. In doing so, you should isolate the problem. Most useful permanently.

And the best way to achieve this is with a good and sustainable measurement of the power quality in your system. With this simple setup, you can determine if altered power quality is present at all. If this is the case, you can see via time stamp exactly when these occurred and whether they even had an impact on your valuable medical equipment.

In the next step you can initiate the analysis of the measurement data. Depending on the depth of know-how, with your own specialist staff or external specialistsbrought in. In doing so, you will find out the cause and can initiate appropriate electrical optimizations.

In turn, the permanent measurement helps you to check the effectiveness of the measures introduced. One could well say that this approach is equivalent to an ISO-certified management system. A PDCA. This is exactly what is considered under the heading “Demand Side Power Quality” or in short “DSPQ” on the part of IEC TR 63191.

Conclusion: If something does not work as you expect, a change in network quality may be the cause. If you have any questions about the topic, just get in touch here. We wish you every success in optimizing your plants and systems. Your team of Power Quality as a Service.